The present invention relates to the field of tooling useful in assembling and maintaining motor vehicle suspensions.
Motor vehicle shock absorbers include helical springs which need to be compressed in order to separate them from the shock absorber member proper or to extract the suspension unit fitted with the shock absorber from a vehicle.
Numerous types of spring compressor are known for this purpose. All of them comprise an actuator (mechanical, electrical, hydraulic, or pneumatic) comprising at least two elements that are telescopically movable relative to each other, with each element having a grip member associated therewith for co-operating with the spring (a portion of a turn of the spring for each member) in order to compress it. Those various spring compressors differ from one another firstly by the means for attaching the grip members to the actuator elements, and secondly by the shapes of the grip members depending on whether they have continuous tracks for cooperating with the spring (referred to as cups) or whether they comprise two arms fixed and/or hinged to the attachment portion and having some gutter-shaped ends for receiving the turn of the spring that is to be manipulated (referred to as claws as in document EP-A-1 046 469).
With cups, at least the middle zone of the track has on its inside margin a big flap that forms a radial abutment for the turn of the spring. With claws, the portion of the jaw carrying the arm hinges includes a kind of hook (a small cradle) which receives the spring turn and which performs the same function as the above-mentioned flap.
Each of those two types of jaw possesses its own advantages and drawbacks. Cups provide the spring with support over a line of contact along which load is better distributed than with claws, where at best three point zones come into contact with the spring, so that there are high levels of stress concentration at those locations. Cups are of fixed shape which means that it is necessary to have several sets of cups for manipulating the springs of different dimensions that are to be found on the market, whereas, because of the way the arms are hinged, a single set of claws can encompass a much wider variety of spring sizes.
Both cups and claws are often ill-adapted to taking hold of suspension spring turns close to the end bearing plates of the springs. Unfortunately, with certain shock absorbers, it is appropriate to manipulate the springs as close as possible to those plates in order to eliminate the effects of the end turns of the springs relaxing while the central turns are being compressed, where such relaxing opposes the desired shortening of the spring in order to make disassembly possible.
The present invention seeks to ally the advantages of claws and of cups while eliminating most of their drawbacks, and with the additional advantage of requiring only a single set of jaws for taking action on the great majority of suspension springs present on the market.